PROJECT SUMMARY Improving individual's health and well-being is of paramount importance not only to their own success but also to the nation's and ample evidence suggests that greater educational attainment predicts increased health and longevity. The mechanisms explaining this link, however, are not well understood. Research indicates that the intensity and duration of light exposure offer potent signals to our brain to regulate circadian physiology and may be linked with cognitive performance and overall wellbeing, at least among adults but we know little about the effects of lighting on children. Given that school occurs during natural daylight hours, it is plausible that daylighting in classrooms will predict indices of sleep, and via its effects on sleep may influence children's learning and health outcomes as well as teacher well-being. The proposed project will significantly advance the scientific knowledge base about the importance of daylighting in sleep, learning, and health. Such evidence would go a long way towards altering building legislation to create ?healthy places? in contexts where children and their teachers spend significant portions of the daylight hours and would offer innovative avenues for improving classroom quality via improved teacher well-being. Through the analysis of subjective, objective, and observational data collected from a diverse sample of 400 children and their teachers, this innovative project will begin to elucidate the pathways by which early educational experiences might impact learning and will generate much needed new knowledge about the role that both structural (e.g., number of windows) and process (e.g., teacher social-emotional well-being) features of the classroom play in producing high-quality classrooms. The first objective is to investigate direct associations between exposure to daylight in the classroom and children's learning-related skills, achievement, health behavior, and physical health outcomes. We propose that children who are exposed to more natural light as well as higher quality light will demonstrate better learning and health outcomes than their peers. The second objective is to test the indirect pathways from daylight exposure in the classroom to children's learning and physical health via their health behavior (e.g., sleep duration and quality). We expect that greater exposure to high quality natural light will be associated with better learning-related skills, achievement, and health via longer sleep and better quality sleep. Finally, the third objective is to determine whether daylight exposure in the classroom is directly associated with teacher social-emotional well-being (e.g., fewer depressive symptoms, lower feelings of burnout, lower stress) and indirectly associated with classroom quality (e.g., instructional support, behavior management, classroom climate, and student-teacher relationship quality) via teacher social-emotional well-being. We expect that exposure to daylight will predict better quality sleep and longer sleep which will, in turn be associated with lower teacher-reported depressive symptoms and better overall adjustment. Finally, we expect that teacher well-being will predict better improved classroom quality, which is related to better learning outcomes.